[Objective] In order to explore the yield potential of cassava, the responses of new cassava varieties to fertilizer quantity was investigated. [Method] A comparative experiment was carried out on 5 new fertilizer-tolerant high-yield cassava varieties（Guire 8, Guire 9, Guire 10, Xinxuan 048 and Guiken 09-26） with the normal-level fertilization groups of these varieties as controls. [Result] The results showed that：（1） increasing fertilizers could significantly improve the stem and leaf yield of cassava;（2） increasing fertilizers could reduce the dry matter content of cassava; and（3） different varieties differed in fertilizer tolerance, and the fertilizing amount should be determined according to specific varieties. [Conclusion] Guire 10 and Xinxuan 048 are suitable for being cultivated at a high fertilizer level, and the remaining three varieties（Guiken 09-26, Guire 8 and Guire 9） are suitable for being cultivated at a normal fertilizer level.
The research explored effects of cultivation methods on growth, yield and quality of cassava. The results showed that the mulching treatment by direct seed- ing, the mulching treatment by transplanting, and the exposed treatment by trans- planting performed excellently in bringing seedling stage forward, improving germina- tion rate, yield and quality. For example, seedling emergence stages were 36, 31 and 31 d earlier; germination rates improved by 19.24%, 14.29% and 14.29%; yields grew by 41.98%, 26.72% and 11.45%; starch contents increased by 3.50%, 2.10% and 1.40%, respectively. Therefore, cassava in the mulching treatment by direct seeding is characterized by earlier seedling emergence stage, high germination rate, high yield and quality.
Using potato plants overexpressing spermidine synthase（SPDS） gene as experimental materials, changes in chlorophyll content, malondialdehyde（MDA） content and superoxide dismutase（SOD） activity of potato leaves under low temperature stress were determined. According to the results, chlorophyll content of experimental plants showed a decreasing trend; MDA content of 01-47 was significantly higher than that of Atlantic; MDA content of 01-6 and 01-49 was significantly lower than that of Atlantic; SOD activity of 01-6 and 01-47 was higher than that of Atlantic. Potato lines 01-6 and 01-47 can be further cultivated to breed new cold-resistant potato varieties.
